1. Field of the Invention
The present invention relates to an exposure apparatus, a calibration method, and a method of manufacturing an article.
2. Description of the Related Art
With miniaturization and large-scale integration of circuit patterns in semiconductor integrated circuits, it has become more important in an exposure apparatus to control the position of a substrate stage with high accuracy. Therefore, a measurement device which measures the position of the substrate stage is supported by a structure formed by a high rigidity material that hardly deforms so as to make a position deviation of the measurement device less likely to occur.
However, the structure may deform due to a force that acts on it due, for example, to vibration conducted from a support table which supports it, or a reaction force generated upon movement of the substrate stage. When this occurs, the position of the measurement device attached to the structure deviates. Such a position deviation of the measurement device leads to an error in position measurement of the substrate stage. To prevent this problem, Japanese Patent No. 4229348 proposes a method of calculating a correction coefficient using an evaluation substrate on which a plurality of patterns are formed to overlay each other, based on the position deviation information of the overlaid patterns, and the difference in force that acts on the structure in forming each pattern, and correcting a measurement error based on the correction coefficient.
An exposure apparatus described in Japanese Patent No. 4229348 calculates a correction coefficient using an evaluation substrate on which a plurality of patterns are formed to overlay each other, based on the position deviation information of the overlaid patterns, and the difference in force that acts on the structure in forming each pattern. However, when a correction coefficient is calculated using an evaluation substrate on which a plurality of patterns are formed to overlay each other, the position of the substrate stage remains almost the same in forming a first-layer pattern and in forming a second-layer pattern. Therefore, the position deviation of the overlaid patterns, and the difference in force that acts on the structure in forming each pattern are small, so the use of the correction coefficient in the exposure apparatus described in Japanese Patent No. 4229348 is insufficient to allow successful calibration of a position control system of a substrate stage.